1. Field of the Invention
This invention relates generally to small computing devices such as laptop computers and in particular, providing a heat removal system that is efficient in both space and heat removal.
2. Description of the Related Art
Compact computing devices such as laptop computers, netbook computers, etc. have become ever smaller, lighter and more powerful. One factor contributing to this reduction in size can be attributed to the manufacturer's ability to fabricate various components of these devices in smaller and smaller sizes, assembling the components in ever more dense configurations, and in most cases increasing the power and or operating speed of such components. As processor power and speed has increased, however, so too has the excess heat generated. As the density of the internal components has increased, the ability to efficiently remove the excess heat generated by those operating components having a high heat flux has been become ever more difficult and costly.
A heat pipe is a heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between the hotter and colder interfaces and is therefore well suited for use in laptop computers, and other high density, compact computing environments. A typical heat pipe consists of a sealed pipe or tube made of a material with high thermal conductivity such as copper or aluminum. The heat pipe includes a working fluid, (or coolant), chosen to match the operating temperature of the compact computing device. Some example fluids are water, ethanol, acetone, sodium, or mercury. (Clearly, due to the benign nature and excellent thermal characteristics, water is used as the working fluid in consumer products such as laptop computers.) Inside the heat pipe's walls, an optional wick structure exerts a capillary pressure on the liquid phase of the working fluid. The wick structure is typically a sintered metal powder or a series of grooves parallel to the heat pipe axis, but it may be any material capable of exerting capillary pressure on the condensed liquid to wick it back to the heated end. It should be noted, however, that the heat pipe may not need a wick structure if gravity or some other source of acceleration is sufficient to overcome surface tension and cause the condensed liquid to flow back to the heated end.
Space or volume is at a premium in compact computer environments and it is essential that any heat removal system must be able to maximize heat transfer while minimizing the space occupied. In addition to minimizing the space required, it is desirable that the heat removal system be relatively inexpensive to fabricate. The cost of fabrication is relatively high when the heat removal system is fabricated from especially dedicated and unique components as distinguished from being fabricated from stock materials.
Although the prior art effectively dissipates heat from electronic devices, there is a continuing need for alternative designs that do not substantially add additional height to the existing Z stack height, that effectively dissipate heat and are relatively inexpensive to fabricate.